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<h2>
<a NAME="ShowAlpha"></a>ShowAlpha, ShowRed, ShowGreen, ShowBlue
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<p><code>ShowAlpha </code>(<var>clip, string pixel_type</var>)<br>
<code>ShowBlue  </code>(<var>clip, string pixel_type</var>)<br>
<code>ShowGreen </code>(<var>clip, string pixel_type</var>)<br>
<code>ShowRed   </code>(<var>clip, string pixel_type</var>)<p><code>ShowAlpha </code>
shows the alpha channel of a RGB32 clip, available in <em>v2.53</em>. <code>ShowBlue</code>
/ <code>ShowGreen</code> / <code>ShowRed</code> shows the selected channel of a RGB clip, available in <em>v2.56</em>.
<p>In <em>v2.54</em> <code>ShowAlpha</code> now returns RGB, YUY2, or YV12 via the
<var>pixel_type</var> argument. The latter two can be used to layer an RGB clip with alpha
transparency data onto a YUV clip using the 3-argument form of <code>Overlay</code>, because
when setting <var>pixel_type</var> to YUY2 or YV12 the luma range is [0,255].
<p>In <em>v2.56</em> <code>ShowAlpha/Red/Green/Blue</code> now returns RGB24, RGB32,
YUY2, or YV12 via the <var>pixel_type</var> argument. For RGB32 output the selected
channel is copied to all R, G and B channels, but not the Alpha channel which
is left untouched. For YUV output the selected channel is copied to the Luma
channel, the chroma channels are set to grey (0x80).
<p><b>Examples:</b>
<pre># shows alpha channels of clip
AviSource(&quot;clip.avi&quot;)
ShowAlpha()</pre>
<pre># swaps red and blue channels:
AviSource(&quot;clip.avi&quot;)
MergeRGB(ShowBlue(&quot;YV12&quot;), Last, ShowRed(&quot;YV12&quot;))</pre>

<p><b>Changelog:</b></p>
<table border="1" width="29%">
  <tr>
    <td width="5%">v2.56</td>
    <td width="95%">added ShowBlue, ShowGreen and ShowRed</td>
  </tr>
</table>

<p><kbd>$Date: 2005/10/03 16:49:04 $</kbd></p>
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